Grinding machine



Nov. 27, 1956- w. H. WOOD GRINDING MACHINE 3 Sheets-Sheet 1 Filed Nov. 6, 1,953

INVENTOR.

'WALzAcE H. W000 BY HTTOENEY Nov. 27, 1956 w. H. WOOD GRINDING MACHINE 3 Sheets-Sheet 2 Filed Nov. 6, 1953 INVENTOR. WALLACE H W0 A TTOE Y United States Patent-O GRINDING MACHINE Wallace H. Wood, Worcester, Mass.,

Company, Worcester, Mass, chusetts assignor to Norton a corporation of Massa- Application November 6, 1953, Serial No. 390,631 6 Claims. (CI. 51-95) The invention relates to grinding machines and more particularly to a hydraulically operated grinding mac me.

One object of the invention is to provide a simple and thoroughly practical hydraulically operated grinding lically actuated pawl to actuate the feed wheel and an independent stop pawl precisely to stop the feed wheel in a predetermined position. vide a fluid motor for rotating the feed screw rapidly to move the wheel slide either toward or from the work piece to position the wheel relative to the work piece to be ground. Another object is to provide a hydraulically operated clutch mechanism whereby the feed.

wheel is automatically declutched during a rapid positioning movement of the wheel slide.

Other objects will be in part obvious or in part pointed out hereinafter.

In the accompanying drawings, in which is shown one 'of the various possible embodiments of the mechanical features of the invention, f Fig. 1 is a fragmentary front elevation of the improved grinding machine;

' Fig.2 is a fragmentary vertical cross sectional view through the grinding machine, showing the wheel feeding mechanism;

Fig. 3 is a hydraulic diagram of the hydraulic control mechanisms of the machine; and

Fig. 4 is a fragmentary view of the upper portion of the feed pawl, partly in section, on an enlarged scale, showing the ball clutch.

An improved hydraulically operated universal-type grinding machine has been illustrated in the drawings comprising a base which serves as a support for a longitudinally reciprocable table 11. arranged to be traversed or reciprocated longitudinally on a flat way 12 and a V-way 13 formed on the upper surface of the base 10.

The table 11 serves as a support for a headstock 14 having a headstock center 15 and also for a footstock 16 having a footstock center 17. The headstock center 15 and the footstock center 17 are arranged to rotatably support the opposite ends of a work piece to be ground.

The base 10 also serves as a support for a transversely movable wheel slide 21 which is arranged to slide transversely on the usual V-way and flat way (not shown) on a wheel slide base 22. The wheel slide 21 is provided on its upper surface with a cylindrical aperture 23 which mates with a correspondingly shaped surface formed on the under side of a swivel head 24. The

Another object is to pro The table 11 is "ice swivel head 24 serves as a support for a transversely adjustable wheel head 25 which supports a rotatable grinding wheel 26. A clamping bolt 27 is provided for locking the Wheel head 25 in a predetermined adjusted [R ition on the swivel head 24. It will be readily apparent from the foregoing disclosure that the swivel head 24 may be angularly adjusted relative to the wheel slide 21, and the wheel head 25 may be adjusted transversely relative to the swivel head 24 to facilitate setting up the machine.

In order to provide an angularly feeding movement of'the wheel slide 21, the wheel slide base 22 is provided with a downwardly projecting cylindrical surface 28 which mates with a correspondingly shaped aperture formed in the upper surface of a base plate 29. The wheel slide base 22 may be clamped in adjusted angular position on the base plate 29 by means of clamping bolts (not shown) which ride in a circular T-slot 30 formed in the upper surface of the base plate 29.

The grinding wheel 26 may be driven by an electric motor 31 which is mounted on the upper surface of the wheel head 25.' A motor shaft 32 is connected by driving belts (not shown) with the grinding wheel spindle 33. The driving belts are contained within a belt guard 34.

A suitable wheel feeding mechanism is provided for feeding the wheel slide 21 transversely toward and from the work piece to be ground. This mechanism may comprise a rotatable feed screw 35 which is rotatably supported by anti-friction bearings 36 and 37 carried by the wheel slide base 22. A half nut 38 depend-s from impart a feeding movement to the wheel slide 21 in any i .angular position of the wheel slide base 22, the shaft 41 is arranged with its axis coinciding with the axis of .the cylindrical surface 28. A bevel gear 42 is keyed onto the lower end of the shaft 41. The bevel gear 42 meshes with a bevel gear 43 which is rotatably journalled in a pair of spaced anti-friction bearings 44 and 45. The bearings 44 and 45 are fixedly mounted relative to the base plate 29. Arotatable shaft 46 is slidably keyed within a sleeve 47 formed integral with the beveled gear 43. The left hand end of the shaft 46 is rotatably journalled within a sleeve 48 which is in turn rotatably supported by a pair of anti-friction bearings 49 and '50 carried by the base 10. A gear 51 is formed integral with the sleeve 48 and meshes with a gearf52 mounted on a shaft 53 which is arranged to be rotated by a manually operable feed wheel 54.

In order to facilitate disconnecting the feed wheel 54 from the feed screw .35, a one-tooth clutch 55 is provided between the sleeve 48'and the shaft 46. A clutch member 56 is keyed onto the sleeve 48. A slidably mounted clutch member 57 is slidably keyed onto the shaft 46 and is arranged to be moved into or out of engagement with the clutch member 56. A compression spring 58 surrounds the shaft 46 and is interposed between the clutch member 57 and a collar 59 which is fixedly mounted on the shaft 46. The compression spring 58 serves normally to maintain the clutch member 57 in operative engagement with the clutch member 56 so that a rotary motion of the feed wheel 54 will be'transrn-itted through the gear mechanism above described to rotate the shaft 46 and thereby transmit a rotary motion to the feed screw 35 to impart a transverse feeding movementto the wheel slide 21. i A- hydraulically operated mechanism is provided-for 3 actuating the clutch 55. This mechanism comprises a cylinder 95 having a slidably mounted piston 96. The piston 96 is fixedly mounted on the left hand end of a piston-rod 97 (Fig 2). The right hand end ofthepiston red 9! is arranged toengage a vrockarm .98 which is pivotally supported by a-stud 99. The rock arm 98 is provided with a stud or pin 160 which ridesin a groove 101 formed in the-clutch member57. When fluidtunder .pressu'reis passed through a pipe 102,.the piston'96 together with the piston-rod 97 will be moved toward the right to rock the rock arm 98 in a counter-clockwise direction so as to move the clutch member 57 toward the right against the compression spring 58 thereby disengaging the clutch.

The'feed wheel 54 is adjustably connected to a-gear 60which is keyed to rotate the gear 52. A small gear or pinion 61 carried by a micrometer feed adjusting mechanism 62 connectsthe feed wheel 54 with .the gear 60.

The grinding wheel feeding mechanism is preferably provided with two pawls for controlling 'the infeeding movement of thegrinding wheel. One pawlis provided which serves only as a stop to positively terminate the rotation of the feed wheel to control work sizing, whereas the second, pawl is in the form of an actuatingpawl which oscillates to-impart a rotary motion to the -feed wheel. By utilizing two pawls,:on e for stoppingsand one for feeding, a precise control of the feed mechanism about the axis of the shaft 53 is provided with a stud 68 whichpivotally supports a feed pawl69. The upper end of' the feed pawl 69 is provided with a small gear '70 which is arranged to mesh with the gear 60. An 'overrunningball clutch 70a is provided between the small .gear 70 and the feed pawl 69. 'The' ball clut'eh70a' is a well known clutch which is in extensive commercial use. The small gear 70 is fixedly mounted on a rotatable Qstud'lllb supported on the upperend of the feed pawl l 69. A ball or roller carrying cage-70c is fixedly mounted on the stud 70b and is provided witha plurality of spring pressed balls'or rollers 70d which ride in wedge-shaped grooves formed in the periphery of the cage 700. 'The Y cage'70c is arranged to rotate within a cylindrical aperture 70e whichis fixed relative to the feed pawl.69. It will be apparent from the foregoing 'dis'closurethat the .g'ear 70 and the-cage 70c. arefree to rotate relative-to "the feed-pawl69 in a clockwise direction only. The ball clutch 70ais arranged sotha-t when the armf67 is rocked ina clockwise direction the gear70 will roll idly inmesh with the gear 60 and when therocharm'67 is. moved in a counter clockwise direction, the" ball iclutchlholds the gear 70 against rotation so that. it imparts a rotary movement to'the. gear 60 which is transmitted'through the mechanism previously described to rotate the feed screw 35. A boss 71 fixedly mounted .on the front ofthe ma- I chine base supports an adjustable stop screw l2 which limits the'counter-clockwise movement of the rock arm '67 thereby facilitating adjustment of thefeeding stroke "of the pawl'69.

A hydraulically operated mechanism is provided for actuating the feed pawl 69 comprising a cylinder 73 which contains a slidably mounted piston 74. The piston 74 is connected to the lower end of a piston rod 75. Theupper end of the piston rod 75 is operatively connected to .an

'arm 76 formed integral with the rock arm 67 so that movement of the piston 74 will be imparted to rock the arm 67 and thereby transmit the desiredrnotion tothe teed pawl 69. Fluid under pressureisnormally .sup- .plied through both of the pipes 77 and 78 to a pair of amass cylinder chambers 79 and 80 respectively-normally-to provide a pressure on'both sides of the piston74 'e xeept when it is desired to produce a feeding movement. A control valve '81 which is actuatedby antlin timed relation with the table reciprocating mechanism in a manner to he hereinafter described is provided for exhausting fluid from one or the other of the cylinder chambers 79 or 80. A startstop valve 82 actuated by a manually operable knob 83, is providedto facilitate rendering the hydraulic feed operative or inoperative as desired.

A fluid pressure systemis provided for supplying fiuid under pressure to the various operating mechanisms of the machine. Thiszsystem may comprise a motor-driven fluid pump 85 which draws fluid through a pipe*-86=from a fluid reservoir.87.and passes fluidunderpressure through a pipe 88 to the operating mechanisms of the machine. A pressure relief -valve -89 is provided in the pipe line 88 to facilitate passing excess fluid under pressure directly through an exhaust pipe 90 into the reservoir 87 so. as to maintain the desired operatingpressure within the fluid system.

A manually operable table traverse wheel '105 is provided for imparting a manual traversing movement to the work table 11. This mechanismhas ,not been illustrated in detail, since it is identical with that shown in rny prior U. S, PatentNo.2,534,937 dated December '19, 1 950, 'to which reference may be had fordetails of disclosure not "contained herein.

A hydraulically operated mechanism is provided for imparting a longitudinal reciprocatory movement-to the work table 11. This mechanism may comprise a cylinder '110 whichis'fixedlysupported on the underside of the tablell. The cylinder contains .a slidably mounted piston lll which is.connected by a double endpiston rod '1 1211 3; the opposite ends of which areconnected to bracket '114 and respectively which are fixedly mounted on the machine base 10.

A suitablecontrol valve mechanism is provided whereby the table 11 may be readily started andstopped when desired. A table actuated pilot and reversing valve mechanismare provided for controlling the admission .toand exhaust ofiluidf'from the table cylinder 110. Thiscontrol mechanism consists ,of a pilot valve 116,.a reversing valve 117, and a start-stop valve 118. The reversing valve 117 "is a piston-type valve comprisingavalve stem 127 havinga plurality of valve pistons, 128, 1 29 and formed integrally therewith. An actuating spool 131 is mountedon' the righthand end of the valve stem 127.

The pilot valve116 is similarly a piston type valve comprising a valve stem 119 having ajplurajlity of valve pistons 120, 1 21, 122 and 123'formed integrally there- An actuating spool 124 is mounted on the right hand-end ofthe valve stem 119. The pilot yalve111'6 is normally held in a central position by means of a balanced spring mechanism comprising apairpfbalauced compression springs 125 and 126. The sp rings 12 5and 126- serve normally to maintain thepilot valve 116 in. the

"positionillustratedin Fig. 3.

The start-stop valve 118 is also a piston typeyalve comprising a valve stem. having a pluralitylof .valve pistons 136, 137, 138'and 139 formed integrally .therewith. A"V'-port'140 is formed in the valve piston 138 "which is arrangedwhen the valve 118 is in a start position to control the exhaust of fluid from the cylinder 110 and thereby to control the speed of movement of'the table 11. A serrated portion 141 formed integral with thevalve stem 135 is engaged'by a, spring-pressed ,detent 142 supported'bythe casing of. the valve 118. The serrated portion 141 and'the' detent 142 serve to maintain jthe valve stem" 135 and the V -port in the'desiredrotaryadjust'ed'position during axialmovement-oflthe valvel stem 135 when shifted to start and. stop position so as ,to

.facilitate starting and stopping the. table,.1 1 without disturbing theadjustment ofthe V-p ort 14.0.

A spool-shaped member 143,.on the valve-stern 135 is connected by astud 144 with a pivotally mounted-startst op lever 145. J Thedever 145;is supported bya stud. 114

which is in turn'fixedly mountedon the front ofthe machine base 10. A knob 147 is mounted on the left hand end of the valve stem to facilitate a rotary adjustment of the V-port so as to regulate the speed of movement of the work table 11.

Assuming the start-stop lever is shifting in a counter-clockwise direction into a start position, fluid under pressure in the pipe 88 enters a valve chamber located between the valve pistons 129 and 130 of the reversing valve 117 and passes out through a pipe through a central passage 151 in the piston rod 112 into a cylinder chamber 152 at the left hand end of the cylinder 110. Fluid under pressure entering the cylinder chamber 152 causes the cylinder 110 and the table 11 to move toward the left (Fig. 3). During this movement-of the table 11, fluid within a cylinder chamber 153 exhausts through a central passage 154 in the piston rod 113, through a pipe 155 into a valve chamber located between the valve pistons 128 and 129 of the reversing valve 117 and passes out through a pipe 156, through the V-port 140 in the start-stop valve 118, and through an exhaust pipe 157 into the reservoir 87. The speed of movement of the cylinder 110 and the table 11 may be adjusted by a rotary adjustment of the knob 147 and the V-port 140. r

The pilot valve 116 is arranged to control the admission to and exhaust of fluid from end chambers 158 and 159 formed in opposite ends of the reversing valve 117. Fluid under pressure in the pipe 88 is admitted at all times to a valve chamber 160 located between the valve pistons 121 and 122 of the pilot valve 116.

When the pilot valve stem 119 is shifted toward the right, a port is uncovered to pass fluid under pressure from the valve chamber 160 through a passage 161, through a throttle valve 162 into the end chamber 159 of the reversing valve 117 to shift the valve stem 127 toward the left at a slow rate until a relatively large port 163 is uncovered by the valve piston 130 to allow fluid under pressure to by-pass the throttle valve 162 and to pass in a relatively large volume into the end chamber 159 rapidly to shift the reversing valve into a reversing position. This movement of the reversing valve 117 serves to pass fluid under pressure through the .pipe 155 into the cylinder chamber 153 to start movement of the cylinder 110 and the table 11 toward the right.

During the shifting of the reverse valve stem 127 toward the left, fluid within the end chamber 158 is free to exhaust through a passage 166 into a valve chamber located between the valve pistons 121 and 122 and out through an exhaust pipe into the reservoir 87.

When the pilot valve stem 119 is shifted toward the left (Fig. 3), a port is uncovered to pass fluid under pressure from the valve chamber 160 through a passage 166, through a throttlevalve 167 into the end chamber 158 of the reversing valve 117 to shift the valve stem 127 toward the right at a slow rate as governed by a throttle valve 167 until a relatively large port 168 is uncovered by the valve piston 128 to allow fluid under pressure to by-pass the throttle valve 167 and to pass in a relatively large volume into the end chamber 158 to snap the reversing valve 117 rapidly into a reverse position. This movement serves to position the reversing valve 117 in the position illustrated in Fig. 3. r A manually operable reversing lever 170 is mounted on the front end of a rock shaft 171 which is rotatably mounted on the machine base 10. The lever 170 is shown diagrammatically in Fig. 3 as provided with a pin or stud 172 which :rides within a groove 173 formed in the spool 131. A manual actuation of the lever 170 serves to shift the reversing valve stem 127 in either direction manually to reverse the direction of movement of the table 11.

It is desirable to provide a suitable table actuating mechanism for'automatically actuating the reversing valve -117 "and the pilot valve 116. A- reversing lever 175 is pivotally mounted on a stud 17 6; The upper end of the lever 6 175 is provided with a stud 177 which is arranged in the path of a pair of adjustable table .dogs178 and 179 which determines the. length of the reciprocatory stroke of the table 11. The lower end of the reversing lever 175 is provided with a stud 180 which rides within a groove 181 formed in the spool 124. It will be readily apparent from the foregoing disclosure that a rocking movement of the lever 175 will be imparted through the stud 180 to shift the pilot valve stem 119,in either direction.

The lower end of the lever 175 is provided with a gear segment 182 which meshes with a gear segment 183 formed on the upper portion of a rock arm 184. The rock arm 184 is pivotally mounted on a stud 185. The lower end of the rock arm 184 is provided with a stud 186 which rides within an elongated slot 187 formed within a link 188 which is pivotally connected by a stud 189 with the manually operable reversing lever 170. The elongated slot 187 provides a lost motion connection between the manually operable lever 170 and the table actuated lever 175. The elongated slot 187 is positioned so that actuation of the lever 175 by the table dogs 178 and 179 serves to positively shift the reversing valve 117 to cut off exhaust of fluid from the table cylinder 110 thereby stopping the table movement. At the same time the pilot valve 116 has been positively shifted from a central position to admit fluid to either the end chamber 159 or the end chamber 158 of the reversing valve 117. The elongated slot 187 is of suificient length to allow unrestricted rapid movement of the reversing valve 117 into the reverse position to start the table movement into the reverse direction. After the table starts its movement in the reverse direction, the elongated slot 187 serves to allow released compression of the balanced springs 125 and 126 to return the pilot valve 116 to a central position.

It will be readily apparent from the foregoing that movement of the table 11 serves to positively shift the reversing valve 117 precisely to stop the longitudinal movement of the table and at the same time to actuate the pilot valve 116 so that fluid under pressure passing at a controlled rate serves to complete the shifting of the reversing valve 117 into the reverse position thereby starting the movement of the table 11 in the reverse direction. By regulating the throttle valves 162 and 167, the interval of dwell between the positive stopping of the table and the reversal of the reversing valve 117,may be readily controlled.

The hydraulically operated feeding mechanism for automatically producing an infeeding movement of the grinding wheel is preferably arranged so that the infeed occurs during the period of dwell at the ends of the reciprocatory stroke of the table 11. The control valve 81 is preferably actuated by and in timed relation with the shifting of the reversing valve 117. As illustrated in Fig. 3, a rod or link is connected by a stud 196 with the manually operable reversing lever 170. The other end of the rod 195 is connected by a stud 197 with a stem 200 of the control valve 81. The valve stem 200 is provided with a plurality of spaced integral valve pistons which form a plurality of valve chambers 201, 202, 203 and 204.

The valve 81 is preferably arranged so that the timing of the valve is reset ahead of the dead center of the reversing stroke. As illustrated in Fig. 3, a slidably mounted sleeve 206 surrounds the valve piston and is slidably supported within a valve casing 207. The sleeve 206 is arranged to be moved in an axial direction either by means of a shoulder 208 on the valve stem 200 at one end or a collar 209 at the other end. The sleeve 206 is provided with a plurality of ports which correspond with the spacing of the ports in the valve casing 207. The ports in the sleeve are enlarged adjacent to the periphery of the sleeve so that in a position of the sleeve 206, they are in full communication with the ports in the valve casing. The sleeve 206 is arranged so that it has an axiaL stroke of approximately As inch relative to the casing.

A friction plunger 210 carried by the casing .207 fric- ;tinally engages a plane surface formed on the sleeve 206 to maintain the sleeve against axial movement except .when moved by the valve stem 200.

When the valve stem 200 is moved toward the left {@Fig. 3) by actuation of the reversing lever 170, the valve pistons slide within the sleeve 206 until the collar 209 engages the end of the sleeve 206 and continued movement of the valve stem 200 then slides the sleeve 206 toward the'left to reset the-ports therein. The resetting of the sleeve 206 serves to advance the position of the with the knob 83 in an on position. Fluid under pressure passing through the pipe 88 may at all times pass through the pipe 77 into the cylinder chamber 79 to main tain pressure on the-upper face of the piston 74. With the valve 82 positioned as shown in Fig. 3, fluid under pressure from the pipe 88 may also pass through the chamber 245 in the valve 82, through a central passage 246, through a pipe or passage 247, through the chamber 201 in the valve 81 and through the pipe 78 into the cylinder chamber 80. Due to the larger etfective area on the underside of the piston 74, the pistonwill be moved upwardly to move the arm 67 into engagement with the stop screw 72 and to maintain the parts in this position during the normal traversing movement of the table 11.

When the lever 170 is shifted in a counter-clockwise direction by movement of the table dog 79 toward the left, the valve stem 200 starts moving toward the left to out off the passage of fluid to the pipe 78 and allows fluid to exhaust from the cylinder chamber 80 through the pipe 78, into the valve chamber 202, through a central passage into the valve chamber 204 where it may exhaust through the pipe 218 into the reservoir 87. Due to the fact that fluid under pressure is at all times being passed into the cylinder chamber 79, the piston 74 will be moved downwardly to cause an upward movement of the feed pawl 69 during which movement the gear 70 rolls idly over the teeth of the gear 60 so that it is ready for a downward infeeding movement. Continued movement of the valve stem 200 toward the left moves the collar 209 into engagement with the sleeve 206 after which the valve sleeve 206 moves toward the left together with the valve stem 200. This movement continues until fluid under pressure passing through the passage 247 enters the valve chamber 203 to pass through the pipe 78 into the cylinder chamber80 to cause an upward movement of the piston 74 thereby rocking the feed pawl 69 in a downward direction. During this downward movement, the ball clutch locks the gear 70 to the feed pawl 69 so that a rotary motion is imparted tothe gear 60 therebyproducing an infeeding movement of the grinding wheel before the movement of the table 11 is started in the reverse direction.

In order to eliminate air in the hydraulic system it is desirable to provide suitable means 'for automatically bleeding air from the system during operation of the machine. A pair of bleeder pipes 215 and 216 are connected to opposite ends of the table cylinder 110. The bleeder pipes 215 and 216 are connected to the feed control valve 81 so that the pressure side of the cylinder 110 is automatically vented. The sleeve 206 is provided with a valve chamber 217 by means of which fluid vented through either of the bleeder pipes 215 and 216 may be exhausted through the valve 81 and through-the said startstop valve 82, through an exhaust pipe 218 into the reservoir 87. It will be readily apparent from the foregoing disclosure that the pressure side of the cylinder 110 operation. As shown in Fig. 3, a rotary type fluid motor 220 is providedhaving a motor shaft 221. Azbevel gear 222 mounted on the left'hand end of the shaft 221 meshes with the bevel gear 42. It willbe readily :apparent that rotary motion of the motor 220 will be transmitted through shaft 221, the bevel gear 222, the bevel gear 42, the shaft 41, the bevel gears 4039 to impart -a rotary motion to the feed screw 35. I

A control valve 223 is provided for controlling the admission to and exhaust of fluid from the fluid motor 220. The valve 223 is preferably a piston type valve comprising a valve stem 224 having a plurality of spaced valve pistons 225, 226, 227 and 228 formed integrally therewith. The valve pistons 225, 226, 227 and 228 form spaced valve chambers 229, 230 and 231. Fluid under pressure from the pressure pipe 88 passes through a valve chamber 232 in the start-stop valve 118, when the latter valve is in the stop position. Fluid under pressure passing through the valve chamber 232 passes through the pipe 157 into the valve chamber 230 of the valve 223. The valve pistons 227 and 228 are narrower than the adjacent ports so that fluid under pressure entering the valve chamber 230 may pass around the pistons 226 and 227 respectively into valve chambers 229 and 231 respectively and exhaust through either a pipe 233 or a pipe 234 into the exhaust pipe 218. A pair of pipes 235 and 236 are connected between the fluid motor 220 and the valve 223. In the position of the valve 223 (Fig. 3), both of the pipes 235 and .236 communicate with the valve chambers 229, 230 and 231 of the valve 223 so that fluid may readily by-pass from one side of the fluid motor 220 to the other thereby facilitating a manual feeding movement when desired. The valve stem 224 is normally held in a central position as illustrated in Fig. 3 by means of a compression spring 237.

A manually operable control valve lever 238 is fixedly mounted on a rock shaft 239 on the front of the'machine base. The inner end of the rock shaft 239 is operatively connected by means of a stud 240 with a groove 241 'formed in the valve stem 224. It will'be readily apparent from the foregoing disclosure that when a rapid positioning movement of the grinding wheel slide is desired,'the control lever 238 may be rocked either in a clockwise or counter-clockwise direction (Fig. 3) to shift the valve stem 224 so as to pass fluid under pressure either through the pipe 235 or the pipe 236 to start the motor 220. The direction of movement of the control lever 238, determines the -direction of movement of the wheel slide.

After the wheel slide has been moved rapidly to the desired position the control lever 238 will then be released and the compression of the spring 237 automatically returns the valve stem 224 to a central or neutral position as illustrated in Fig. 3.

It is desirable to provide means for obtaining relatively slow traversing speedof the table 11 for a grinding wheel truing operation. This is preferably accomplished by means of a throttle valve 250 -(Fig. 3) in the pipe line 157-which serves to control the rate of exhaust of fluid from the table cylinder when the start-stop valve '118.is in a start position. An actuating knob 251 on the front of the machine base serves to control the position of the throttle valve 250. When theknob isrocl-tedin a count '-Clockwise direction into the Grind position illustrated in Fig. l, the knob engages a stop 252 whichpos} tions the throttle valve 250 so that unrestricted exhaust offlu mflv p s hrough e P urin thencrma'l reciprocation of the table 11. Whenit is desired to true the grind n 'wheel, the knob 251 is rocked in :a clockwise diresiifil into .a p sit on in. enssssiasnt .w fihan adjustable stop 253 which serves to shift the throttle valve 250 so as to partially cut off the fluid exhausting through the pipe 157 to provide a slow traverse of the table 11 during a grinding wheel truing operation. By adjusting the position of the stop 253, the rate of the truing speed of the table 11 may be regulated as desired. After this speed is determined, the stop 253 may be clamped in adjusted position and the table may be operated either at a grinding or truing speed by merely shifting the control knob 251 into either a Grind or a True position.

The operation of the improved grinding machine will be readily apparent from the foregoing disclosure. Assuming all adjustments to have previously been made, the work drive motor, the wheel drive motor 31, and the fluid pump motor are started. A work piece to be ground is mounted on the headstock center 15 and the footstock center 17 with the work piece being driven in the conventional manner, namely, by means of a work driving dog (not shown). The'start-stop lever 145 is moved in a counter-clockwise direction (Fig. 3) to open the V-port 140 which allows fluid to exhaust from the cylinder chamber 153 of the table cylinder 110 thereby starting reciprocation of the work table 11. In this position'of the valve fluidunder pressure is conveyed through the pipe 150 into the cylinder chamber 152 to start the table 11 moving toward the left (Fig. 3). The table dogs 178 and 179 are arranged to actuate the reversing lever 175 to reverse the direction of movementof the table in a manner above described at the ends of a predetermined stroke thereof. The feed control valve 81 actuated by and in timed relation with the reversing lever 170 serves automatically to feed the grinding wheel 26 into the work piece being ground during the dwell at reversal at each end of the table stroke. The infeeding movement of the grinding wheel 26 continues intermittently at the ends of the table stroke until the stop abutment 66 on the feed wheel 54 engages the stop surface 65 on the stop pawl 63 positively to stop the infeeding of the grinding wheel when the work has been ground to a predetermined size. During this infeeding movement the feed pawl 69 is os cillated through one complete up and down movement at each reversal of the table to cause a predetermined infeed. The extent of infeed being determined by the setting of the stop screw 72.

When it is desired to stop the operation of the machine, the start-stop lever 145 may be shifted in a clockwise direction (Fig. 3) into the position illustrated to cut off the exhaust of fluid from the table cylinder 110 and thereby to stop reciprocation of the table 11.

If desired the infeed of the grinding wheel may be stopped by turning the knob 83 into an off position in which position fluid under pressure is passed to both the cylinder chamber 79 and the cylinder chamber 80 to hold the piston 74 in an upward position with the arm 67 in engagement with the stop screw 72.

If it is desired to true the grinding wheel, the knob 251 may be rotated in a clockwise direction into engagement with the stop 253 to partially close the throttle valve 250 to restrict the exhaust of fluid from the table cylinder 110 so as to obtain a predetermined slow traversing movement of the table 11 during the truing operation.

If it is desired to rapidly move the wheel slide 21 toward or from the work supporting table 11, this may be accomplished by the hydraulically operated mechanism above described. With the start-stop valve 118 in the position illustrated in Fig. 3, fluid under pressure is passed through the pipe 102 to move the piston 96 toward the right thereby disengaging the clutch 56-57 to render the feed wheel 54 inoperative. In this position of the parts, the control lever 238 may be rocked in either a clockwise or a counter-clockwise direction to shift the valve stem 224 so as to pass fluid under pressure either through the pipe 235 or the pipe 236 to start the fluid set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not'in a limiting sense.

I claim: I I

1. In a grinding machine having a longitudinally reciprocable table, a piston'and-cylinder to reciprocate said table, a reversing valve operatively connected to control the flow of fluid to and'from said cylinder, a transversely movable wheel slide, a rotatable grinding wheel on said slide, a wheel feeding mechanism for said slide including a nut and feed screw to feed said slide in either direction, a manually operable feed wheel to rotate said feed "screw, an adjustable stop abutment on saidfeed wheel, an oscillatable feed pawl operatively connected to actuate said feed wheel, an adjustable stop to limit movement of the pawl in one direction to facilitate adjusting the'extentof the infeed, a fluid motor operatively connected to actuate said pawl, a control valve for saidfluid motor, operative connections between said control valve and the table reversing valve whereby the control valve is actuated by and in timed relation with the table reversing valve so as to impart an infeeding movement to the grinding wheel during reversal, and means including an independent stop pawl arranged to be engaged by said stop abutment positively to limit rotation of the feed wheel so as to stop the infeeding movement of the grinding wheel.

2. In a grinding machine as claimed in claim 1, in combination with the parts and features therein specified of a rapid positioning mechanism for the wheel slide including a rotary fluid motor operatively connected to r0- tate said feed screw in either direction, a manually operable control valve operatively connected to control said motor which is arranged to facilitate starting the rotary fluid motor in either direction so as to cause a rapid approaching or receding movement of the wheel slide, and means normally to hold said control valve in a central position normally to allow unrestricted flow of fluid between opposite sides of said motor to facilitate manual actuation of the feed wheel.

3. In a grinding machine as claimed in claim 1, in combination with the parts and features therein specified of an oscillatable arm to support said feed pawl, means including vertically arranged piston and cylinder to oscillate said arm, said latter piston having differential areas on opposite sides, means continuously to convey fluid under pressure to the upper chamber of the vertical cylinder having the smaller piston area, means including a control valve for controlling the admission to and exhaust of fluid from the lower cylinder chamber, said control valve being arranged normally to admit fluid under pressure to the lower end of said vertically arranged cylinder normally to maintain the piston in an uppermost position with the pawl arm in engagement with the adjustable stop, and operative connections between the reversing valve and said control valve to shift the control valve in one direction at each table reversal, said control valve being arranged during each actuation to facilitate exhaust of fluid from the lower cylinder chamber and thereafter to admit fluid under pressure to the lower chamber vertical cylinder so as to cause one complete oscillation of the feed pawl so as to cause an infeeding movement of the grinding wheel during each table reversal while the table is stationary.

4. In a grinding machine as claimed in claim 1, in combination with parts and features therein specified of an oscillatable arm to support said feed pawl, means including a vertically arranged piston and cylinder to oscillate said arm, said latter piston having differential areas 1 1 La a i aposite sides, means continu usly o convey flu d under P essure l t e-upper cham er o the e t ca sy n sr xlla lr g the maller vpiston rea me ns in lud n a s ui el alv ior c ntr ll ng t dmiss on t d xha s @ixfluid from th l wer ha b r o he e ti l cy inder sa d control valve being arrangednorrnallytoadmit fluid under preSSqre to the lower end of said vertical cylinder morm lly 0 m int in t e P n n an upp r p t wit l hc rmin g em withsaid s op p ati o ,1 c 0nsh tw en.the abl re s g valve and sa co trol .valve to shift the control valve in one direction at each table reversal, said control valve being arranged during each actuation torjaciiitate exhaust of fluid from 531.16 IOWer chamber of the vertical cylinder and thereaft er 2L adm ui unde p e ur t th o e hamb of =,th e rvertical cylinder spas to cause one complete reciprowtion of, the Piston an the eed pawl, d means l d- :iug Asian-stop valve arranged whenin a stopped position tot yepassjluid around said control .valve to prevent infecding of the grinding wheel at table reversal.

5- In a grindin -m ch ne ha in a ran erse y m v ?hle wheel slide, a rotatable grinding wheel on said slide, means-includinga nut and feed screw to feed said slidein either direction, a manually operable feed wheel to actuate. said feed -screw,,rneans including a movable feed pawl 4 rotate said 'feed wheel to impart a feeding movement to the wheel slide, power operated means to move said pawl, and a rapid positioning mechanism for the wheel slide including a fluid motor operatively connected to rotate said" feed screw, a manually operable control valve .fo sa vlii slrapto ar an ed {to aail ate s ar-fiasco; fluid moto in eithsrd eat ri as o ause, rap d-aapr aa rng or r eding mo eme f t e wh el s ide, and m ns no mal y-1Q h ldssaid rontr l ve in a c ntra Po t on no ma y t allow n st i ed fl of fluid between opposite sides of said motor to facilitate manual actuation of thefeed wheel. v

6; In a grinding machine as claimed in claim 5, in cornbination with the parts and features therein specified of a longitudinally reciprocable table, a piston and cylinder to reciprocate said table, a reversing valve for controlling the flow of fluid to and from. said cylinder, a start-stop valve op at v ly c nn t t s r and st p sa d. ta la, a fluid pressure actuated clutch for disengaging thev man- :ually op rab f wheel, a p s and y nders a uate said clutch and operative connections between the start stop valve and the l tter cy nder or dis n ging said clutch when the start-stop valve is in a start position. v

'tSilVen vOct. 23, 1951 

